<?php$installer = $this;$installer->startSetup();$installer->getConnection()->addColumn($installer->getTable('core/url_rewrite'),    'tag_id', 'INT( 10 ) NULL DEFAULT NULL AFTER `product_id`');$installer->getConnection()->addForeignKey(    $installer->getFkName('core/url_rewrite', 'tag_id', 'tag', 'tag_id'),    $installer->getTable('core/url_rewrite'),    'tag_id',    $installer->getTable('tag'),    'tag_id');$installer->endSetup();